脊椎変性疾患に対する手術適応とその変遷

The Chronological Changes in the Operative Indications and Approaches for the Treatment of Spondylosis Deformans of the Spine

はじめに

　変形性脊椎症は脊椎の退行変性に伴う病態であり，椎間板，椎体および椎間関節の変性を意味しているが，加齢に伴って生じる椎間板や終板軟骨の変性，椎間板腔の狭小，椎間板ヘルニア，すべり，亜脱臼，弯曲異常，椎間関節肥厚，靱帯肥厚，骨化，骨棘形成，などを含んで呼んでいる場合が多い^1）。中年以降では多くの人が何らかの脊椎骨の変性を有するが，臨床症状まで呈するものは少ない。しかし，これらの形態変化やそれに伴う圧迫などが進展すると，神経症状を呈する。脊髄を直接圧迫したり，慢性的な圧迫に伴う慢性のくも膜炎を引き起こす。また血管系への圧迫によって虚血性変化が生じ，脊髄の変性や軟化をもたらす。さらに椎間孔内で神経根に圧迫や循環障害を起こしたり，椎骨動脈の循環障害などを招く。肋骨が脊椎の動きを制限している胸椎には少なく，脊椎の可動性が高い頸椎と腰椎にほとんどみられる。

　本稿では脊椎変性疾患の中で頻度の高い変形性頸椎症，変形性腰椎症について，手術適応と変遷について述べてみたい。

Abstract

　Spondylosis deformans of the spine occurs due to degenerative changes of the intervertebral disc, vertebral body and hypertrophy of the interarticular joint.　Such changes, including narrowing of the disc space, degeneration of the endplate, spur formation, hypertrophy of the facet joint, spondylolisthesis, abnormal curvature of the spine, are generally observed in the elderly people.　Neurological abnormalities may develop because of spinal cord compression or circulation disturbances.　In such cases, surgical intervention may be considered.

　Significant decompression of the spinal cord and root and reconstruction of the load-sharing ability of the spine are the most important purposes of surgical interventions.

　However, the most appropriate surgical approach for cervical spondylotic myelopathy remains controversial.　Previous comparative series tend to favor the anterior surgical approach for patients with cervical spondylotic myelopathy arising from focal or segmental lesions.　Surgery via the posterior approaches offers significant advantages for the treatment of patients with multilevel disease.　However, laminectomy should be avoided in cases with straightening or reversal of the curvature of the cervical vertebral column.　The appropriate surgical approach should be decided after careful consideration of the detailed biomechanical properties of the lesions.

　Various techniques of decompressive laminoplasty have been developed exclusively in Japan.　Clinical evidence regarding the applicability of these methods is inconclusive; however,some significant improvements have been observed after the reconstruction of posterior elements of the spine in some cases.　Here,the chronological developments in the surgical procedures used for treating-cervical and lumbar lesions have been briefly described.